imsd, imsd-ofonod: let polkit decide call control, not the account name

The system-bus policies granted net.catcrafts.IMS1 and org.ofono to root
and to the account `user`, postmarketOS's default name, so on a unit
whose account is called something else dbus denied every Dial from the
dialer — nothing in imsd's journal, nothing on screen. A field user
found it by trial (alyx report 14, 2026-09-20; ims ledger F14).

Let any local account reach both names and have the daemons decide:
placing, answering or ending a call needs polkit's
net.catcrafts.IMS1.Voice (the active local session; not an ssh login, an
inactive session or a system service account). imsd-ofonod asks about
its own callers, since its calls reach imsd as root. Reads such as the
status and the call list are not gated, and a refusal is logged with the
sender; a `--session` run, the development mode without root or polkit,
leaves the gate off. The check is ImsdBus, a small GLib module both
daemons link; the package depends on polkit.

An upgrade restarts both daemons (the previous commit), so the open
policy faces the old, ungated daemons only until the apk transaction
ends.

Tested on the dev phone (KPN) in builds of this series; not every path
has run there.

implementations/ofonod.cpp

@@ -45,11 +45,12 @@ plugins/provider/ofono/ — get these wrong and the plugin silently ignores us:
 
 Runs as root because `org.ofono` is a system-bus name (policy in
 packaging/org.ofono.conf). It does no I/O beyond D-Bus: every call decision
-stays in imsd. Everything happens on the GLib main loop, so there is no
-locking.
+stays in imsd. Its calls reach imsd as root, so it asks polkit about its own
+callers (ImsdBus): call control is net.catcrafts.IMS1.Voice, as on imsd.
+Everything happens on the GLib main loop, so there is no locking.
 
   --session   own org.ofono on the session bus and talk to imsd there
-              (development: no root, no policy file)
+              (development: no root, no policy file, no polkit)
   IMSD_BUS=session|system   override only the imsd side of that choice
 */
 
@@ -57,6 +58,7 @@ locking.
 #include <glib-unix.h>
 
 import std;
+import ImsdBus;
 
 namespace {
 
@@ -315,7 +317,9 @@ void HandleCallMethod(GDBusConnection*, const gchar*, const gchar* objectPath, c
     g_dbus_method_invocation_return_dbus_error(inv, "org.freedesktop.DBus.Error.UnknownMethod", "no such method");
 }
 
-const GDBusInterfaceVTable CallVtable = { HandleCallMethod, nullptr, nullptr, {} };
+bool IsRead(std::string_view method) { return method == "GetProperties" || method == "GetCalls" || method == "GetModems"; }
+constexpr char ErrAccessDenied[] = "org.ofono.Error.AccessDenied";
+const GDBusInterfaceVTable CallVtable = { imsd::bus::Gated<HandleCallMethod, IsRead, ErrAccessDenied, Log>, nullptr, nullptr, {} };
 
 guint RegisterObject(const char* xml, const char* path, const GDBusInterfaceVTable* vtable) {
     GDBusNodeInfo* node = g_dbus_node_info_new_for_xml(xml, nullptr);
@@ -596,9 +600,9 @@ void HandleSsMethod(GDBusConnection*, const gchar*, const gchar*, const gchar*,
 }
 
 const GDBusInterfaceVTable ManagerVtable = { HandleManagerMethod, nullptr, nullptr, {} };
-const GDBusInterfaceVTable ModemVtable = { HandleModemMethod, nullptr, nullptr, {} };
-const GDBusInterfaceVTable VcmVtable = { HandleVcmMethod, nullptr, nullptr, {} };
-const GDBusInterfaceVTable SsVtable = { HandleSsMethod, nullptr, nullptr, {} };
+const GDBusInterfaceVTable ModemVtable = { imsd::bus::Gated<HandleModemMethod, IsRead, ErrAccessDenied, Log>, nullptr, nullptr, {} };
+const GDBusInterfaceVTable VcmVtable = { imsd::bus::Gated<HandleVcmMethod, IsRead, ErrAccessDenied, Log>, nullptr, nullptr, {} };
+const GDBusInterfaceVTable SsVtable = { imsd::bus::Gated<HandleSsMethod, IsRead, ErrAccessDenied, Log>, nullptr, nullptr, {} };
 
 // ---- imsd events ------------------------------------------------------------
 void PublishVoiceState() {
@@ -727,6 +731,7 @@ int main(int argc, char** argv) {
         if (std::string_view(argv[i]) == "--session") session = true;
 
     GBusType ofonoBus = session ? G_BUS_TYPE_SESSION : G_BUS_TYPE_SYSTEM;
+    imsd::bus::AuthorizeCalls = !session;
     std::string imsdBusName = EnvOr("IMSD_BUS", session ? "session" : "system");
     GBusType imsdBus = imsdBusName == "session" ? G_BUS_TYPE_SESSION : G_BUS_TYPE_SYSTEM;